Accelerating device



y 4 I R. G. BEVRRYIY 2,251,105

ACCELERATING v DEVICE Filed May 3, 1939 2 Sheets-Sheet i INVENTOR. RUSSELLGBERRY ATTORNEY.

July 29, 1941.

' R. G. BERRY 2,251,105

ACCELERATING DEVICE Filed May 3, 19.39 .2 Sheets-Sheet 2 INVENTOR. Russzu. CBERRY ATTORNEY.

Patented July 29, 1941 ACCELERATING DEVICE Russell G. Berry, Maplewood, Mo., assignor-to Carter Carburetor Corporation, St. Louis,-Mo., a corporation of Delaware Application May 3, 1939, Serial No.271,518

1 Claim.

This invention relates to internal combustion engine carburetors and more particularly to accelerating devices therefor.

With the advent of the downdraft carburetor and its conventional dispostion; that is in a position above the exhaust manifold in a zone of comparatively high temperature, a fault in carburetors called percolation becomes accentuated.

This percolation or untimely exuding of fuel into the mixing conduit is caused by vapor pressures in fuel chambers or passages which, due to their location, become excessively heated under certain operating conditions, and particularly during periods of inoperation immediately following periods of substantial power output operation of the engine in hot weather. It will be seen also that any partial evaporation of fuel confined within an accelerating fuel chamber will have a detrimental effect upon the eiiiciency of any plunger type accelerating device by reason of the compressability of the fuel when in a gaseous form.

It is an object of this invention to provide an accelerating device in which the pressure build-up, due to vaporization of fuel therein, is prevented by a constant sized relief opening thereinto.

It is a further object of this invention to provide a generally new and improved accelerating fuel pump plunger embodying a pressure relief opening and being adapted to economical production.

Other objects and advantages will be noted upon referring to the following description and accompanying drawings in which:

Fig. 1 is a diagrammatic representation of a downdraft carburetor showing an accelerating device constructed in accordance with my invention and adapted to be used with a flat plunger shaft.

Fig. 2 is an enlarged, fragmental View of the accelerating fuel chamber and pump plunger as shown in Fig. 1.

Fig. 3 is an enlarged perspective view of the upper plunger leather retaining washer, shown in Figs. 1 and 2.

Fig. 4 is an enlarged fragmental view of an accelerating device disclosing another embodiment of my invention adapted to be used with a round plunger shaft.

Referred to the drawings, numeral l indicates a main carburetor body casting having an air inlet casting 2 and an outlet casting 3 suitably attached thereto. A choke valve 32 mounted for-rotation on the shaft 33 controls air inlet and a throttle valve 35 attached to throttle'shaft 36 for rotation therewith controls the carburetor outlet 31.

A flange 4 formed as a part of the carburetor outlet casting and arranged for attachment to a companion flange 5 on the engine intake manifold 6 by the studs 1 and nuts 8 is provided.

The engine exhaust manifold 9 is arranged to provide a hot spot in the intake manifold by means of the jacket l0.

A-constant level fuel chamber H formed as a part of body member I is provided and a substantially constant level of fuel, as indicated by the dot-dash line A-A is maintained therein by means of a float l2 and the inlet valve 13.

A cylindrical accelerating fuel chamber l4, vertically disposed in the constant level fuel chamber and having an accelerating pump plunger I5 arranged'for reciprocation therein, is provided. Communication between the constant level chamber Il'and the accelerating fuel chamber is provided'in the form of passages 16, H and I8. An. inletcheck valve I 9 is provided to control this communication.

An accelerating fuel discharge system for dis charging into the mixing conduit, comprising outlet 20, passage .Zl, discharge check valve 22, passage 23, passage 24 and discharge nozzle 25' is provided. A slot 56 in the wall of the accelcrating fuel chamber l4 extending downwardly below the level of fuel, permits fuel to flow into the chamber I4 above the plunger, thereby providing, at all times, a. liquid seal and thus preventing air leakage into the chamber l4 below the piston I5 during the intake stroke.

A means is provided for moving the accelerating pump plunger in accordance with throttle movements, comprising a plunger shaft 26, pivotally attached at 27 to a lever 28 which, in turn, is pivotally mounted at 29a, link 30 and a lever 3| which is rigidly attached to the throttle valve shaft 36.

A spring 3'! normally urging the accelerating pump plunger upward is provided to take up fit clearance at pivotal attaching points in the pump plunger to throttle valve linkage, thus eliminating any lost motion therebetween upon opening movements of the throttle.

The accelerating pump plunger l5 comprises a main guide member 38. A cup-formed, pliable member 39, a thin flexible retaining washer 4!] and a comparatively thick retaining washer 4|. Members 38, 39, 40 and 4| all have similar rectangular perforations at their centers, as indicated at 42 in Fig. 3, for the purpose of assembly on the reduced portion 43 of the flat plunger shaft 26. The foregoing plunger members are assembled and held firmly against the shoulder 44 by upsetting the end of shaft 26 as indicated at 45.

A spring 54 retained within a groove 55 formed in the plunger member 38 for the purpose, normally urges pliable cup member 38 against the wall of the accelerating fuel chamber l4.

Passages 46, 41, 48 and 49 through the members 38, 39 and M], respectively, provide a means for relieving pressure which may be formed below the pump plunger |5 by vaporization.

It will be understood that the passage 49 and 49A through the thin, flexible retaining Washer 40 is relatively quite small as compared to the accelerating fuel chamber inlet lb or discharge outlet 20, and that the accelerating device is so proportioned that the effect of the constant relief passage upon the pump discharge is negligible.

The upper retaining washer 44 is provided with the formed groove 5| rotated so as to coincide, upon assembly, with the passages 45, M and 48.

To guard against misalignment of passages in assemblying members 38, 39 and 40 and misalignment of the passages with the formed groove 5| which would fail to provide a continuous relief passage, I have provided additional passages 46A, 41A and 18A. It will be seen in view of this provision and the provision of a rectangular perforation at the center of the plunger members, that it would be impossible to assemble the plunger without providing a relief passage as intended.

It will be seen that upon a downward or discharge stroke of the pump plunger, fuel will issue at a high velocity from passage 48 and will be deflected as it strikes the transverse groove 5| thereby being prevented from spraying directly upwardly and causing objectionable leakage through the plunger shaft opening 52 in the constant level chamber cover 53.

The modification of my invention disclosed in Fig. 4 is adapted to be used with a round plunger shaft indicated at 26A. The plunger members 38A, 39A, 49A and 4|A are similar in form to corresponding members in Fig. 2, however, a round hole is provided at the center of these members instead of a rectangular perforation. Also the vertical vent passages are omitted. In this arrangement, a passage 56 and a cross passage 51 in the plunger rod provide a constant relief. Cross passages 58, in member 38A and 59 in plunger rod 26A provide a communication between passage 56 and the spac 60.

Threaded means SI for firmly holding the assembled plunger members against the shoulder 62 is provided.

In operation, fuel is supplied to the constant level chamber through the inlet passages 75 and 16.

Fuel for normal and high speed operation is supplied to the mixing conduit through metering jet 63, passage 54 and discharge nozzle 55.

Fuel for idling operation is supplied by a conventional idling system comprising an idling fuel jet 65, passage 61, passage 68, restriction 69, passage 10, passage 1|, discharge port 12 and air bleeds I3 and 74.

Upon closing movements of the throttle, fuel is drawn into the accelerating fuel chamber l4 through passages I8, I! and I6.

Upon opening movement of the throttle, accelerating fuel is discharged into the mixing conduit through passages 20, 2|, 22, 23, 24 and discharge nozzle 25.

The detailed description and structure shown is intended to be illustrative not limiting, and various modifications within the scope of the following claim are possible.

I claim:

For use in an accelerating device, a plunger and shaft assembly comprising a flat stamped metal strip having a shoulder formed near one end by a reduction in width and having a perforation near the opposite end to receive a link pin, a composite plunger comprising a generally cylindrical guide member, a cup shaped pliable sealing member, a flexible retaining washer and a rigid retaining washer, said plunger members all having non-circular, central perforations for slip-fit assembly on the reduced end of said stamped strip in an order reversely as recited, said guide member, said pliable sealing member and said flexible retaining member having two additional diametrically opposite perforations similarly located with respect to said central noncircular perforation so as to form continuous passageways when said members are assembled, said rigid retaining washer having a radial groove extending to its outer edge and located so as to register with one of said passageways when assembled.

RUSSELL G. BERRY. 

